Follow-Up of Cardiac Implantable Electronic Devices—Remote Monitoring and in Person: Implementation and Guidelines

In-Person Monitoring

In-person monitoring with a structured in-clinic follow-up protocol by physicians or allied health professionals in a clinic or medical institution has been the conventional standard for device follow-up. Face-to-face evaluation permits history-taking, physical examination, electrocardiography, and radiography as indicated. Interrogation of the device is performed using a programmer for bidirectional communication with the CIED. This has traditionally been wand-based but more recently has been done with wireless telemetry using a programmer located within 3 m. Device function, including capture and sensing thresholds, may be reviewed. Response to medical therapy may be disclosed (e.g., for AF). Programmed settings and functions may be reprogrammed if necessary to optimize device operation and individualize parameters according to patient need (“actionable” encounters). The frequency of this may depend on the indication for the encounter (e.g., a routine scheduled check versus unscheduled encounters to follow a particular condition or specific symptoms).

In-person monitoring is required following implantation before hospital discharge, for wound checks within 2 weeks, and then again at 6 to 12 weeks to set chronic parameters for pacemakers, ICDs, and CRTs. This time period is significant because system-related problems (e.g., threshold increase, perforation, and need for revision) tend to cluster in the early postoperative period.

Subsequent follow-up schedules vary according to facility, physician preference, and available resources. Consensus recommendations advocate a minimal recommended schedule of device follow-up every 3 to 6 months at the clinic for ICDs and CRT-Ds and every 6 to 12 months for pacemakers, but with increased frequency (e.g., monthly) in response to product advisories and recalls. Follow-up of implantable loop recorders (ILRs), which play an important role in detection of infrequent arrhythmias and evaluation of syncope, is relatively unstructured and is performed according to facility protocols (and/or patient symptoms). Scheduled checks occurring with this frequency represent a huge number of evaluations estimated to be almost 4 million encounters annually in the United States alone. At the same time, efficiency with regard to problem discovery rates have until recently been unknown. In addition, this protocol does not account for unscheduled checks, an added burden on already saturated device clinics. The occurrence of significant cardiac or arrhythmic symptoms (e.g., shock therapy, palpitations) or if a CIED alert is detected (e.g., audible alert) traditionally has required emergent clinic attendance and CIED interrogation. In the mid-2000s, a succession of advisories demanding higher frequency of follow-up overwhelmed clinic follow-up capacity, motivating the development and application of RM technologies.

Transtelephonic Monitoring Without Interrogation

RM of pacemakers has occurred for decades using transtelephonic monitoring (TTM) using modem technology. This system converts electrocardiographic information into sound to communicate over telephone lines to a decoding machine, which changes the sound back into the “rhythm strip.” This was introduced in the early 1970s to monitor the longevity of pacemakers and was implemented for remote surveillance of sensing and capture, as well as lead and device malfunction. It permitted frequent monitoring of pacing rate, determination of the underlying rhythm, and timely detection of battery depletion. Although extensively used, it was restricted to pacemakers, depended on active patient participation (and hence was vulnerable to adherence issues), and delivered only a brief snapshot of the cardiac rhythm and thus was likely to miss intermittent problems. Indeed, in a recent trial, only 3 of 190 events were found on TTM with discovery of the remainder requiring (delayed) inpatient assessment.

Modern Systems

Modern systems permit access to the extensive data recorded in diagnostic memory of current-generation CIEDs. Each system is proprietary and works only with compatible devices from the same manufacturer ( Table 40-1 ). All RM systems require a small external device to communicate programmed parameters and diagnostic data stored in the CIED memory, either with active patient participation (via a wand) or automatically and fully independent of patient or physician interaction (“wandless”). In the latter ( Fig. 40-1 ), an encrypted telemetric signal is sent from the CIED to a transceiver. This relies on a CIED-initiated remote transmission using a Medical Implant Communication Service (402-405 MHz) or Industrial, Scientific, and Medical (902-928 MHz) radiofrequency band allocated for implanted medical devices. The only requirement is that the patient be within a distance of approximately 6 ft (approximately 2 m) from the transceiver. These may be at preset time intervals of variable frequency (e.g., every 3 months or more frequently). The effect of transmission frequency on battery longevity varies among different proprietary systems. One system automatically transmits daily (Home Monitoring; Biotronik). Once transferred from the CIED to the patient device, encrypted data are uploaded via telephone landlines or cellular transmissions to a secure central database or data-processing facility organized by the manufacturer. Details are posted on a secure website for review by authorized personnel. The system can be programmed to download data at specific times and/or dates, usually when the patient is sleeping adjacent to the base unit. Generally, the transmitted parameters of different RM systems are programmable according to individual needs. Alert messages may be communicated to physicians via email, text messaging, fax, or telephone call, according to the clinical urgency of the event. The customization of alerts for individual patients may be Internet-based, obviating the need for patient attendance (e.g., Biotronik's Home Monitoring) ( Fig. 40-2 ) with very rapid data delivery ( Fig. 40-3 ), or it may require the use of a programmer during an ambulatory visit (e.g., CareLink; Medtronic). In some systems, patients may be informed of alert messages by an audible signal (beep) or vibration from the CIED. RM reports are typically generated and sent with different alert levels, enabling the caregiver to respond according to their relative urgency. For example, event notifications may be delivered to the physician or clinic, either as “red alerts” signifying conditions that might leave the patient without appropriate device therapy or as “yellow alerts” of lesser urgency regarding patient and device functions. A unique feature of the Latitude system is the ability of ambulatory patients to connect weight scales and blood pressure cuffs to allow the remote identification of sudden changes in heart failure (HF) status.

Clinical Applications

Since 2008, investigators in a large number of randomized controlled trials have compared strategies of traditional in-person evaluations (IPEs) versus remote management for postimplant CIED follow-up. These trials are chronologically summarized in Table 40-2 . In addition, trialists have explored the ability of RM to detect problems early in order to potentially improve patient outcomes. The trials have involved a variety of proprietary technologies in different health care models. Collectively, they have shown the superiority of RM for achieving the follow-up goals of patient adherence to structured follow-up protocols, improvement in device clinic efficiency, and, recently, documented improvement in patient outcomes when directly compared with in-person methods. Central to these results has been the use of automatic wireless RM (and not RI). These results form the basis for fresh recommendations. This changes the paradigm for the use of remote technology from occasional replacement of routine appointments, for patient and clinic convenience, to a system of nearly continuous monitoring with most IPEs initiated in response to alert notifications communicated by RM, to improve the quality and efficiency of patient care.

Outpatient Clinic Workload Reduction and Optimization

CIED evaluation at prescribed intervals (every 6 months for PMs and every 3-6 months for ICDs and CRT-Ds) may be facilitated by RM. Results consistently show that replacement of in-person follow-up visits with RM can reduce IPE volume by about 50% in patients over at least 1 year with all types of CIEDs (see Table 40-2 and Fig. 40-4 ). Safety was not compromised, as demonstrated in the TRUST and ECOST studies. The EVOLVO study showed that the rate of emergency department or urgent in-office visits was 35% less in the RM arm than in the IPE arm. Furthermore, there was a 21% reduction in the rate of total health care visits for HF, arrhythmias, or ICD-related events. The REFORM trial showed that ICD follow-up using adjunct RM can reduce the number of IPEs by 63.2% with no difference in hospitalization rate or mortality. Although most patients in the aforementioned trials had ICDs and CRT-Ds, the PREFER and COMPAS trials demonstrated similar results for early detection and reduction in outpatient clinic load for patients with pacemakers followed with RM. (Though not tested, patients with an ILR with wireless data transfer capability should be enrolled in an RM program, given the daily availability of diagnostic data.) In all these trials, RM also shortened the time to detection of arrhythmic events to a median of 1 day compared with more than 30 days with quarterly conventional care (see Fig. 40-4 ). This interval was defined by time elapsed from event onset to physician evaluation; that is, it was a test not merely of transmission time (a technological feature) but of clinical practice.

In summary, several large, randomized, prospective trials conducted with different proprietary RM technologies in different countries, inclusive of pacemakers, ICDs, and CRT-Ds, have ensured follow-up continuity of a large patient volume, avoiding unnecessary in-hospital patient evaluation, and shown consistently that replacement of most routine in-person visits with RM permits reduction in health care visits and earlier problem detection, without compromising safety.